FIG. 1 is a partially schematic, cross-sectional illustration of a typical microelectronic device package 10 in accordance with the prior art. The package 10 can include a microelectronic die 20 carried by a support structure 30 and protected by an encapsulant 50. The die 20 can have die solder balls 22 that provide an internal electrical connection to the support member 30. The support structure 30 can include package solder balls 11 that provide external electrical coupling to other devices or circuits. Accordingly, the package 10 can be integrated into consumer or industrial electronic products, such as computers, telecommunication devices and the like.
In one aspect of the arrangement shown in FIG. 1, the package 10 can include an underfill material 40 that adheres the die 20 to the support structure 30 and protects the die solder balls 22 during encapsulation. The underfill material 40 typically extends along the support structure 30 outwardly from the die 20, and upwardly from the support structure 30 along side surfaces 25 of the die 20. One drawback with this arrangement is that the underfill material 40 typically has a coefficient of thermal expansion (CTE) that is substantially different than that of the other components of the package 10. Accordingly, when the package 10 undergoes thermal excursions, for example, during cooling after elevated temperature processes, the underfill material 40 can contract more than the other components within the package 10. As a result, the underfill material 40 can place the side surfaces 25 of the die 20 under tension, which can cause cracks 21 to form in the die 20, and/or can delaminate material from the side surfaces 25. The underfill material 40 can also exert a tensile force on the support structure 30, which can cause the support structure 30 to delaminate. The foregoing cracks and/or delaminations can reduce and/or eliminate the ability of the package 10 to function properly.